package top.sigetech.springcloud.lb.impl;

import org.springframework.cloud.client.ServiceInstance;
import org.springframework.stereotype.Component;
import top.sigetech.springcloud.lb.LoadBalancer;

import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * 手写简单负载均衡
 */
@Component
public class MyLB implements LoadBalancer {
    private AtomicInteger atomicInteger = new AtomicInteger(0);

    public final int getAndIncrement(){
        int current;
        int next;
        do {
            current = this.atomicInteger.get();
            next = current >= Integer.MAX_VALUE ? 0 : current+1;
        }while (!this.atomicInteger.compareAndSet(current,next));
        System.out.println("******第几次访问next:"+next);
        return next;
    }

    @Override
    public ServiceInstance instances(List<ServiceInstance> serviceInstances) {
        int index = getAndIncrement() % serviceInstances.size();
        return serviceInstances.get(index);
    }
}
